Method for preparing magnetic ink and dry pigment particles used therefor
AssigneeVideojet Systems International, Inc.
InventorWing Sum Vincent Kwan
Life of this patent
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Abstract
A method for making magnetic ink compositions is disclosed. The magnetic particles used in the ink are prepared from an aqueous slurry. A surface derivatizing agent is added to the slurry to render the magnetic pigment particles hydrophobic. The particles then sink to the bottom of the slurry, and the bulk water is then removed. After air drying, dry magnetic pigment particles are provided. The particles will be hydrophobic, and thus will have superior resistance to water as compared to previously known magnetic pigment particles. Magnetic ink compositions are formulated from the magnetic particles.
Claims15
A method for preparing modified iron oxide containing pigment particles, comprising contacting an aqueous slurry of iron oxide containing pigment particles with a surface derivatizing agent having one or more phenolic and 1,3-diketo moieties or a surface derivatizing agent which is a phenol substituted with one or more substituents selected from the group consisting of cycloalkyl, alkenyl, alkynyl, alkoxy, keto, diketo, pyrido, benzo, alkylcarbonyl, halo, cycloalkylcarbonyl, hydroxyalkyl, haloalkyl, alkoxyalkyl, unsubstituted alkyl, and combinations thereof.
A method for preparing hydrophobic iron oxide pigment particles, comprising preparing an aqueous slurry of iron oxide containing pigment particles, such that the pigment particles are present in an amount from about 2% to about 20% by weight of the slurry;
- adding a surface derivatizing agent having one or more phenolic and 1,3-diketo moieties or a surface derivatizing agent which is a phenol substituted with one or more substituents selected from the group consisting of cycloalkyl, alkenyl, alkynyl, alkoxy, keto, diketo, pyrido, benzo, alkylcarbonyl, halo, cycloalkylcarbonyl, hydroxyalkyl, haloalkyl, alkoxyalkyl, unsubstituted alkyl, and combinations thereof to the slurry in an amount less than about 10% by weight of the pigment particles;
- mixing the surface derivatizing agent into the slurry to render the pigment particles hydrophobic;
- and recovering and drying the hydrophobic pigment particles.
Dependencies are inferred from the claim text.